48 



ANATOMICAL STEUCTUEE OF THE OLIVE. 



activity of the pericambium in developing phellogen (Ph.) and cork 

 (Co.) (fig. 13), besides a secondary cortex (C*) (fig. 14), to say 

 notliing of the continued cambial cell divisions on the inner face of 

 the leptome, as observed already in the much thinner lateral roots. 



The result of these various in- 

 creases (fig. 14) is the develop- 

 ment of a broad zone of cork, the 

 development of a secondary cor- 

 tex (C*), the development of a 

 closed sheath of pericambial 

 stereome (St.), and finally from 

 the cambial strata the develop- 

 ment of secondary leptome and 

 hadrome (L. and H.) with rays 

 of parenchyma (P.). 



The diagram (fig. 15) shows 

 the arrangement of all these tissues except the epidermis and the 

 exodermis, which have, of course, been thrown off before this stage is 

 reached. The center of the root possesses remnants of the primitive 

 root stele, from which rays of parenchyma extend toward the sec- 



FiG. 13.— Transverse section of a lateral root of the first 

 or second order of an olive tree, showing the develop- 

 ment of phellogen (Ph.) and cork (Co.). (X 120.) 



Camb^ 



Fig. 14.— The same transverse section shown 

 in figure 13 of the root of an olive tree, 

 showing the development of a SM-ondary 

 cortex (C*) and parenchyma ( F . ) rays from 

 the cambial (Camb.) strata, (x 120.) 



Fig. 15.— Diagram of the root of an olive tree, showing 

 the general arrangement of tissues described in figures 

 11 to 14, inclusive. (X 22.\.) 



ondary cortex (C*). The I'oot of the genus Olea shows the arrange- 

 ment of the several tissues in a remarkably regular way, and the 

 presence of pericambial stereome is interesting. 



192 



